Technology for autonomously controlling the speed of a host vehicle to maintain a proper vehicle-to-vehicle distance between the host vehicle and a preceding vehicle that travels ahead of the host vehicle is disclosed. An application of this type of technology is disclosed in Patent Literature 1. According to the technology disclosed in Patent Literature 1, in order for an adjacent-lane vehicle traveling adjacent to a host vehicle to be capable of easily merging ahead of the host vehicle, the distance between the host vehicle and a preceding vehicle is controlled such that a vehicle-to-vehicle distance greater than or equal to the length of the adjacent-lane vehicle is ensured.
Even if a proper vehicle-to-vehicle distance between the host vehicle and the preceding vehicle is maintained by autonomous vehicle state control, when the adjacent-lane vehicle travels right next to and in parallel with the host vehicle, a driver may experience psychological discomfort, and get stressed due to the adjacent-lane vehicle. In particular, when a large vehicle travels exactly adjacent to the host vehicle, an increasing degree of psychological discomfort is given to the driver.
In the related art, for example, in such a technology disclosed in Patent Literature 1, the psychological discomfort of the driver of the host vehicle caused by a peripheral vehicle is not taken into consideration in the adjustment of the travel position of the host vehicle. For this reason, in the related art, it cannot be denied that the driver is likely to experience strong psychological discomfort due to a vehicle that approaches the host vehicle in the travel position adjusted by autonomous control.